Prosthesis deployment device with translucent distal end

ABSTRACT

A prosthesis delivery and deployment device includes an elongate and flexible outer catheter. The outer catheter has a tubular wall of layered construction, including translucent layers, opaque layers, and a braid composed of helically wound metal filaments. The outer catheter has a translucent distal adapted to constrain a radially self-expanding prosthesis in a radially reduced, axially elongated state. Because the stent constraining region is translucent, an endoscope can be used to visually monitor the stent when so constrained. Radiopaque markers can be mounted to the outer catheter and to an inner catheter used to deploy the prosthesis, to afford a combined visual and fluoroscopic monitoring for enhanced accuracy in positioning the prosthesis, both before and during its deployment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/554,533 filed Jul. 20, 2012, now U.S. Pat. No. 8,535,369, which is acontinuation of U.S. application Ser. No. 12/467491 filed May 18, 2009,now U.S. Pat. No. 8,226,702, which is a continuation of U.S. applicationSer. No. 10/281,017, filed Oct. 25, 2002, which is a continuation ofU.S. application Ser. No. 09/569,445, filed May 12, 2000, now U.S. Pat.No. 6,726,712, which claims the benefit of priority of ProvisionalApplication No. 60/134,267, filed May 14, 1999, the contents of each areincorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates to medical devices for deliveringendoprostheses to predetermined treatment sites within body cavities orlumens, and further deploying the endoprostheses at the selected sites.More particularly, this invention relates to such devices that arecapable of enabling or facilitating a tracking of the endoprosthesesduring deployment.

A variety of patient treatment and diagnostic procedures involve the useof prostheses inserted into the body of a patient and intraluminallyimplanted. Percutaneous translumenal coronary angioplasty (PTCA) andother vascular treatments frequently involve implanting prostheses suchas stents to maintain vessel patency or grafts to shunt blood. Similarimplantations are used in non-vascular procedures, e.g., enteral,billiary, and esophageal applications.

There is a need to accurately characterize the intended implant site tofacilitate proper placement of the prosthesis. There is a further need,just before deployment and during deployment, to ascertain the locationof the prosthesis relative to the intended placement site. One knownapproach to such characterizing and monitoring is angiography, whichinvolves supplying a radiopaque contrast fluid to the cavity or lumen,then radiographically viewing the lumen. This approach, however,provides only a monochromatic, two-dimensional image showing a profilebut no depth of field.

According to another approach, radiopaque markers can be placed on thedelivery/deployment device. Before deployment, the position of theprosthesis within the device is known, and determining the deviceposition in effect accurately determines the prosthesis position. Thisadvantage is lost during deployment, however, and again the image offersneither distinctions in color nor depth of field.

According to yet another approach, the prosthesis can be fabricated atleast in part using a radiopaque material. For example, the filaments ofa stent can be formed of, or may incorporate a core formed of, platinum,tantalum or another radiopaque material. This approach likewise lacksthe capacity for distinction among colors, and imposes limitations uponthe materials used to form the prosthesis.

U.S. Pat. No. 5,411,016 discloses an intravascular balloon catheterhaving a lumen containing an angioscope. A distal portion of thecatheter shaft, surrounded by the dilatation balloon, is transparent,and index markers are provided along the balloon. Thus, objects againstwhich the balloon wall is pressed when the balloon is inflated can bequantified. This structure requires viewing the lumen through thecatheter wall and the balloon wall, and does not address the need formonitoring the position of a prosthesis with respect to its deliverydevice during deployment. This need is particularly apparent inconnection with radially self-expanding prostheses, which areconstrained in radially reduced configurations during delivery, and mustbe released from their confining devices during deployment to permitradial self-expansion.

Therefore, it is an object of the present invention to provide aprosthesis delivery and deployment device that substantially surrounds aprosthesis to retain the prosthesis during delivery to a treatment site,yet facilitates an optical viewing of the prosthesis before and duringits deployment.

Another object is to provide a prosthesis delivery device particularlywell suited to negotiate tortuous intraluminal pathways in the body thatincorporates a translucent carrier segment through which a prosthesiscarried within the device can be optically viewed.

A further object is to provide a process for deploying a radiallyself-expanding prosthesis within a body lumen in which an opticalviewing device is advantageously used to view at least a proximalportion of the prosthesis to visually monitor a location of theprosthesis during its deployment.

Yet another object is to provide a catheter or other device forintraluminal delivery of a prosthesis, that incorporates a prosthesisconfining wall sufficiently light transmissive to enable a viewing ofthe prosthesis through the wall, so that an optical instrumentpositioned within a body lumen outside the catheter can be used toobserve the prosthesis contained in the delivery device, as well astissue surrounding the delivery device.

BRIEF SUMMARY OF THE INVENTION

To achieve these and other objects, there is provided a prosthesisdelivery and viewing device. The device includes an elongate, flexiblecatheter having a tubular catheter wall defining a catheter lumen. Thecatheter, along a distal end region thereof, is adapted to substantiallysurround a body insertable prosthesis and thereby releasably retain theprosthesis within the catheter lumen. The catheter wall, at least alongthe distal end region, is translucent to allow an optical viewing of thebody insertable prosthesis through the catheter wall when the prosthesisis so retained.

Most preferably, the distal end region of the wall is substantiallytransparent, i.e., highly transmissive of wavelengths in the visiblespectrum. Satisfactory viewing is achieved, if the distal end regionwall merely is translucent; more particularly, sufficiently lighttransmissive so that at least about 25% of light impinging directly uponone side of the catheter wall is transmitted through the wall to theother side. A polyether block amide, for example as sold under the brandname Pebax, has been found to be well suited as a catheter wallmaterial, not only due to its relative transparency, but also because itprovides a ductile or flexible catheter wall that bonds well with otherpolymeric material. Certain nylons also can be used, although they arenot as ductile as the Pebax material.

The device is advantageously used as part of a system that also includesan optical viewing device positionable proximate the distal end of thecatheter to facilitate an optical viewing of the prosthesis andsurrounding body lumen or cavity. An endoscope is suitable as such aviewing device.

According to one particularly preferred construction, the catheterincludes an elongate, flexible translucent inner tubular body. Aflexible, translucent first outer tube surrounds and is integral with adistal end region of the inner tubular body. An elongate, flexiblesecond outer tube surrounds the inner tubular body, is integral with theinner tubular body, and is disposed proximally of the first outer tube.If desired, a flexible third outer tube is disposed between the firstand second outer tubes, and contacts the other outer tubes to provide asubstantially continuous profile composed of the three outer tubes. Thisconstruction allows a tailoring of the catheter, to provide a balancebetween two somewhat conflicting needs: sufficient flexibility tonegotiate serpentine pathways; and sufficient columnar strength alongthe catheter length to provide the necessary axial pushing force.

In particular, such tailoring can involve selecting materials ofdifferent durometer hardness for the outer tubes. One highly preferredexample uses a 63 Shore D durometer Pebax material in the first outertube, and a 72 Shore D durometer Pebax material in the second, proximalouter tube which comprises most of the catheter length. To providefurther columnar strength and resistance to kinking, a support structurecan be interposed between the inner tubular layer and at least thesecond outer tube. A preferred structure is a braid of helically woundmetal filaments, e.g., stainless steel or a cobalt-based alloy such asthat sold under the brand name Elgiloy. If desired, the wire braid canextend distally beyond the second outer tube, and thus reside betweenthe inner tubular layer and a proximal portion of the first outer tube,up to about one-half of the first outer tube length. When a third,medial outer tube is employed, it is preferably composed of a materialhaving a 63 Shore D durometer hardness.

The delivery device further can include a prosthesis release componentmounted moveably with respect to the catheter to effect a release of theprosthesis from within the catheter lumen. For example, an elongateflexible member, which can be a tube if desired, is disposed inside thecatheter lumen and either abuts the proximal end of the prosthesis, oris surrounded by the prosthesis along its distal portion. In many casesthe latter arrangement is more desirable, because it enables aretraction of the prosthesis after it is partially deployed, ifrepositioning is deemed necessary.

The delivery device is particularly well suited for use in a process fordeploying a radially self-expanding prosthesis within a body lumen,including:

-   -   a. disposing a radially self-expanding prosthesis in a radially        compressed state within a catheter, surrounded by a tubular wall        of the catheter along a distal end region of the catheter;    -   b. moving the catheter intraluminally to position the distal end        region of the catheter near a selected prosthesis deployment        site within a body lumen;    -   c. with the catheter distal end region so positioned, initiating        a release of the prosthesis from the catheter, and during the        release, using an optical viewing device to optically view at        least a proximal portion of the prosthesis through the catheter        wall, to visually monitor a location of the prosthesis; and    -   d. after completing the release of the prosthesis, proximally        withdrawing the catheter to leave the prosthesis disposed within        the body lumen.

Thus in accordance with the present invention, a prosthesis can beoptically viewed both before its release to insure an accuratepositioning within a body lumen, and during its release to monitor itsposition both with respect to the lumen, and with respect to thedelivery/deployment catheter. An endoscope or other suitable opticaldevice can provide an image that enables the user to distinguish amongcolors, which can be beneficial in recognizing properties of the tissueat the treatment site. Optical images also afford depth of field. Thecapability of optically viewing the lumen and prosthesis when stillcontained within the catheter, combined with fluoroscopic imaging of thecatheter and the prosthesis, provides particularly effective monitoringof the deployment and positioning of the prosthesis.

BRIEF DESCRIPTION OF THE DRAWINGS

For a further understanding of the above and other features andadvantages, reference is made to the following detailed description andto the drawings, in which:

FIG. 1 is a side elevation of a prosthesis delivery and deploymentdevice constructed in accordance with the present invention;

FIG. 2 is an enlarged elevation, partially sectioned to show furtherfeatures of the device;

FIGS. 3, 4, 5 and 6 are sectional views taken respectively along thelines 3-3, 4-4, 5-5, and 6-6 in FIG. 1;

FIG. 7 is a schematic view of a prosthesis deployment and viewing systemincorporating the deployment device;

FIG. 8 is a side elevation illustrating an alternative embodimentdeployment device; and

FIG. 9 is a side elevation illustrating another alternative embodimentdeployment device.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings, there is shown a device 16 for delivering aradially self-expanding prosthesis to a selected treatment site within abody cavity or body lumen, and for deploying the prosthesis, once it ispositioned at the treatment site. The device includes an elongate,flexible outer catheter 18 having a tubular catheter wall 20. Aradiopaque marker 22 is mounted to the catheter near its distal end 24.

Along its axial length, catheter wall 20 is divided into three sectionsor regions: a distal region 26; a medial region or transition region 28;and a proximal region 30. As indicated by the break, the full length ofproximal region 30 is not shown in FIG. 1. The proximal region is by farthe longest of the three regions. The diameter and axial length ofcatheter 18 can vary according to the application and size of the bodylumen involved. Some typical ranges for enteral applications include atotal catheter length of 135-230 cm in conjunction with a distal segmentlength of 7-18.5 cm, a transition region length of 6-7.5 cm, and adiameter of 5-22 French, i.e. about 1.7-3.0 mm.

Distal region 26 extends from distal end 24 to a junction 32 between twoslightly different polymeric materials employed in forming the catheterwall. Along the distal region, the catheter wall preferably istransparent, exhibiting a high transmissivity of energy in the visiblespectrum. Less preferably but satisfactorily, catheter wall 20 istranslucent along the distal region, in the sense that at least 25% ofthe energy in the visible spectrum impinging directly upon catheter 18is transmitted through catheter wall 20 to the other side. A braid 34formed of helically wound intersecting filaments of stainless steel, acobalt-based alloy or other suitable metal, forms a layer of catheterwall 20 beginning at a distal region that is visible due to thetransparency of the polymeric layer surrounding it. The braid extendsproximally to a proximal end 36 of the catheter, provides a reinforcingstructure that increases the columnar strength of medial region 28 andproximal region 30, and also increases radial stability and resistanceto kinking when catheter 18 is bent.

FIG. 2 shows device 16, particularly the distal and medial sections, ingreater detail. Outer catheter 18 includes a catheter lumen 38 that runssubstantially the entire catheter length. An inner catheter 40,contained in lumen 38, is movable axially relative to outer catheter 18.Inner catheter 40 extends lengthwise substantially along the entirelength of the outer catheter. A sleeve 42 surrounds inner catheter 40along a distal portion of the catheter comparable to catheter distalregion 26 in its axial length. A prosthesis, in particular a radiallyself-expanding stent 44, surrounds the inner catheter and sleeve alongthe distal portion of the inner catheter. Stent 44 in turn is surroundedby the distal region of outer catheter 18, constrained by the outercatheter wall in a radially reduced, axially elongated state. Stent 44is radially self-expanding, in that once free of the outer catheter, thestent tends to shorten axially and expand radially to a normal orunstressed shape in which the stent diameter is much larger than thediameter of the outer catheter. Stent 44 is somewhat similar to braid34, in that the stent is composed of oppositely directed helically woundfilaments or wires that intersect one another. However, because thefilaments forming stent 44 typically are smaller in diameter than thefilaments forming braid 34, the filaments of the stent frequently areformed of materials selected for enhanced radiopacity, e.g. a compositeconstruction including a tantalum core within an Elgiloy casing. Aradiopaque marker 45 is located along inner catheter 40, between theinner catheter and the sleeve.

The layered, segmented construction of catheter wall 20 is best seen inFIG. 2. Catheter wall 20 includes an inner layer, i.e. a PTFE liner 46that extends for the length of the catheter. Liner 46 is substantiallytranslucent to transparent, typically with an amber cast. Liner 46typically is etched to improve bonding adhesion to the layers thatsurround it.

The surrounding layers, or outer tubes, include a transparent ortranslucent outer distal layer 48, an opaque outer medial layer 50, andan opaque outer proximal layer 52. Marker 22 is disposed between liner46 and distal outer layer 48. Beginning near the proximal end of outerlayer 48 and extending proximally for the remainder of the catheterlength, braid 34 is interposed between outer layer 48, medial outerlayer 50 and proximal outer layer 52. The outer layers are bonded to theliner. Consequently, the liner, outer layers, marker and braid areintegral with one another.

In accordance with the present invention, materials are selected for theliner and outer layers to impart desired properties that differ over thelength of catheter 18. As noted above, liner 46 is formed of PTFE. Theinside surface of liner 46 preferably is coated with silicone, toprovide a low-friction surface to contact stent 44 and facilitate axialtravel of inner catheter 40 relative to the outer catheter. Liner 46 iscylindrical, and can have for example an inner diameter of 0.117 inchesand a radial thickness of 0.0015 inches.

Over the majority of the catheter length, the next radially outwardlayer is composed of braid 34. The filaments of braid 34 can bestainless steel wires, having a diameter of about 0.015 inches. In oneadvantageous arrangement, 32 wires are wound helically, interbraided ina two-over-two-under pattern, at about 52 pics per inch. The braid anglecan be 110-150 degrees, i.e. 55-75 degree inclines from a longitudinalaxis.

At the distal end of catheter 18, radiopaque marker 22 is provided inthe form of an annular band surrounding liner 46. The band can be formedof a platinum/iridium alloy, and can have a diameter of 0.127 inches andradial thickness of about 0.0015 inches.

Distal outer layer 48 surrounds and is bonded to liner 46. The preferredmaterial for the distal outer layer is a polyether block amide availableunder the brand name “Pebax,” with a 63 ShoreD durometer hardness. Outerlayer 48 is substantially transparent. Accordingly, liner 46 and outerlayer 48 in combination provide a catheter wall region that issubstantially transparent, or at least sufficiently translucent so thatstent 44, when contained within catheter 18 as shown in FIG. 2, isvisible from outside the catheter through the catheter wall. Anotherfavorable property of outer layer 48 is its relatively high flexibility,whereby the distal region is well suited for initial tracking throughserpentine body passages as the catheter is moved toward an intendedtreatment site. Distal outer layer 48 can have a diameter of about 1.17inches, and a thickness of about 0.010 inches.

Medial outer layer 50 also is preferably constructed of the Pebaxpolyether block amide, having the same 63 Shore D durometer hardness.The polymer is combined with a blue dye, and thus forms an opaque layer.Outer layer 50 can have an axial length of about 5 cm, an inner diameterof about 0.129 inches, and a radial thickness of about 0.012 inches. Dueto the contrast between the translucent outer layer 48 and the opaqueouter layer 50, junction 32 provides a clear visible marker that locatesthe proximal end of stent 44 when the stent is radially constrained bythe outer catheter.

Transition region 28 includes the full length of outer layer 50, and inaddition the length of braid 34 extending distally into distal region26. Although the visible distal extension of the braid can include halfthe length of distal region 26 and even more if desired, this extensiontypically is in the range of 1-2.5 cm. The transition region thuscombines braid 34 and the 63 D durometer hardness Pebax polymer, withpart of the polymer being translucent and part being opaque. Transitionregion 28 is flexible, although less flexible than the distal region.The braid reduces kink potential. Proximal outer layer 52 is formed of aPebax polymer having a 72 Shore D durometer hardness. The proximal outerlayer can have an inner diameter of 0.129 inches and a radial thicknessof 0.012 inches, same as the medial outer layer. Also like the mediallayer, proximal outer layer 52 is combined with a blue dye to renderthis region of the catheter opaque. The higher durometer hardness of theproximal outer layer provides enhanced column strength, thus to providethe axial pushing force necessary for advancing the catheter distallythrough body passages.

Less highly preferred but satisfactory results may be achieved whenforming the various catheter wall components using alternativematerials. For example, several grades of nylon including nylon 12 maybe used to form outer layers 48, 50 and 52. A suitable alternativematerial for liner 46 is polyurethane, e.g. as available under the brandname Pellethane. A nylon available under the brand name Amitel issuitable for the outer layers, although better suited for the opaqueouter layers than translucent outer layer 48.

Inner catheter 40 is preferably formed of polyether ether ketone (PEEK).The polymer forming sleeve 42 preferably is substantially softer andmore flexible than the other polymers, so that stent 44 when disposedbetween the catheters as shown in FIG. 2 tends to embed itself into thesleeve.

FIG. 7 illustrates a system 54, including device 16, for delivering anddeploying stent 44 within a body lumen 56. The system includes anendoscope 58 positionable within body lumen 56 proximate distal region26 of the catheter. Although the endoscope is represented schematically,it is to be understood that the endoscope can incorporate a light source60, an optical fiber or other suitable optical path to transmit light tothe distal end of the endoscope, an optical fiber, bundle of fibers orother suitable path to transmit images proximally along the endoscope,and a display terminal 62 for displaying the visible image. The proximalend of outer catheter 18 is coupled to a manifold 64. A handle 66,coupled to inner catheter 40 and movable relative to the manifold,controls axial movement of the inner catheter relative to the outercatheter. Additional fittings 68 are provided for a variety of purposesdepending on the procedure, potentially including accommodating aguidewire, transmitting a therapeutic drug to the distal end of thecatheter, and accommodating a balloon inflation fluid for a dilatationballoon.

System 54 is used in a stent implant procedure as follows. First, aguidewire or guide canula is used to track endoscope 58 to the selectedimplant site. Likewise, a guidewire (not shown) is tracked to the site.

Next, device 16 is loaded onto the guidewire and tracked to the site.The flexibility of the distal section improves cornering through thebody passages on the way to the site. Meanwhile, proximal region 30provides the column strength necessary to push the device toward thesite. Braid 34 provides resistance to kinking, combined with the abilityto track tight radii.

As distal end 24 of the device approaches the treatment site, junction32 between translucent and opaque regions provides a reliable visibleindication to locate the proximal end of the constrained stent 44.

Once the catheter distal end is positioned as desired, stent 44 isdeployed, by pulling outer catheter 18 proximally while controllinghandle 66 to maintain inner catheter 40 in place. Due to the softness ofsleeve 42 and the lubricity of silicone coated liner 46, stent 44 tendsto remain with the inner catheter rather than moving proximally with theouter catheter.

As the outer catheter continues to move proximally, distal end 24 iscarried proximally with respect to the distal end of the stent, thuspartially freeing the stent for radial self-expansion. Because of thetranslucency of the outer catheter wall along distal end region 26,endoscope 58 can be used continuously during deployment to monitor theposition of stent 44, relative to body lumen 56 and relative to innercatheter 40. Moreover, as outer catheter 18 continues to move axiallyrelative to inner catheter 40, radiopaque marker 22 likewise movesaxially relative to marker 45, thus to permit a fluoroscopic monitoringof the outer catheter axial position relative to the inner catheter.Markers 22 and 45 can be positioned such that as marker 22 approachesmarker 45, a limit approaches beyond which deployment cannot bereversed, i.e. when the stent no longer can be drawn back into outercatheter 18 by advancing the outer catheter distally relative to theinner catheter. The combined visual and fluoroscopic monitoring enablesthe user to more precisely confirm an appropriate positioning of thestent before exceeding the limit.

Beyond the limit, outer catheter 18 is moved proximately until stent 44is completely free of the outer catheter. This leaves the stent free toradially self-expand to its nominal diameter. The nominal diametertypically exceeds a diameter of body lumen 56, so that the stentself-expands into an intimate contact with a tissue wall 70 defining thebody lumen. With the implant of the stent thus complete, endoscope 58and device 16 are proximally withdrawn, leaving the stent implanted atthe treatment site.

FIG. 8 illustrates a portion of an alternative embodiment outer catheter72 including a single liner 74 and several outer layers including adistal outer layer 76, medial outer layer 78 and proximal outer layer 80as before. Outer catheter 72 differs from outer catheter 18, in that allthree of the outer layers are translucent or substantially transparent,providing an outer catheter that is translucent or substantiallytransparent over its entire length.

FIG. 9 illustrates an outer catheter 82 of another alternativeembodiment device, including an inner liner 84 and a single outer layer86 running substantially the entire outer catheter length. A bodyimplantable stent 88 is constrained along the distal region of the outercatheter, in a radially reduced axially elongated state. An innercatheter 90 is contained within a lumen 92 of the outer catheter. Ratherthan being surrounded by the stent, inner catheter 90 is disposedproximally of the stent, and movable distally relative to the outercatheter to engage the proximal end of the stent. Catheter 90 deploysthe stent by pushing the stent distally relative to catheter 82. Whilethis approach is suitable for certain procedures, and may reduce thecost of the device, it also lacks the capability of reversing stentdeployment to reposition the stent.

Thus, in accordance with the present invention, a prosthesis can bevisually monitored during its deployment, even when substantially orentirely contained within the deployment catheter. When provided withlayers of differing flexibility over the catheter length, the cathetercan be sufficiently flexible at its distal end for efficient tracking,yet sufficiently rigid along its more proximal regions to insureadequate distal pushing force. Further, radiopaque markers can beemployed to enable fluoroscopic monitoring of device components as wellas visual monitoring of the device and stent, to insure that the stentnot only is properly aligned at the outset of deployment, but remains inthe desired position as it is released from the deployment device.

The invention claimed is:
 1. A method of forming a catheter with alongitudinal length, the method comprising: bonding a distal outer tube,the distal outer tube being either translucent or transparent, to adistal region of an inner tube having a longitudinal length equal to thelongitudinal length of the catheter, the inner tube also comprising aproximal region, and a medial region extending between and connectingthe distal and proximal regions, wherein the distal region of the innertube is either translucent or transparent; bonding a medial outer tubeto the medial region of the inner tube, the medial outer tube beingopaque; bonding a proximal outer tube to the inner tube, the proximalouter tube being opaque; and interposing a support structure between theinner tube and the proximal, medial, and distal outer tubes and bondingthe support structure thereto, wherein the support structure extendsfrom a proximal end of the inner tube to a position that is proximal toa distal end of the inner tube and distal to a distal end of the medialouter tube, the support structure positioned such that a stent disposedin the distal region of the catheter extends distal of the supportstructure.
 2. The method of claim 1, wherein the inner tube comprisesPTFE and the distal, medial, and proximal outer tubes comprise polyetherblock amide.
 3. The method of claim 2, wherein the medial and proximalouter tubes further comprise a dye.
 4. The method of claim 2, whereinthe polyether block amide of the distal and medial outer tubes has alower Shore D durometer than the polyether block amide of the proximalouter tube.
 5. The method of claim 4, wherein the Shore D durometer ofthe distal and medial outer tubes is 63±15 and the Shore D durometer ofthe proximal outer tube is 72±15.
 6. The method of claim 1, wherein thesupport structure comprises metal filaments.
 7. The method of claim 6,wherein the metal filaments are in the form of a braid.
 8. The method ofclaim 1, further comprising coating an inner surface of the inner tubewith silicone.
 9. The method of claim 1, further comprising coupling amanifold to a proximal end of the catheter.
 10. A method for forming aprosthesis delivery system comprising: positioning an inner catheterhaving a handle at a proximal end, the inner catheter comprising a walldefining a lumen and comprising a first inner catheter polymer, in alumen defined by a wall of an outer catheter comprising: an inner tubehaving a longitudinal length equal to the longitudinal length of theouter catheter, the inner tube comprising a distal region, a proximalregion, and a medial region extending between and connecting the distaland proximal regions, the distal region of the inner tube being eithertranslucent or transparent; a distal outer tube bonded to the distalregion of the inner tube, the distal outer tube being either translucentor transparent; a medial outer tube bonded to the medial region of theinner tube, the medial outer tube being opaque; and a proximal outertube bonded to the proximal region of the inner tube, the proximal outertube being opaque; interposing a support structure between the innertube and the proximal, medial, and distal outer tubes and bonding thesupport structure thereto; wherein the inner catheter is movable axiallyrelative to the outer catheter; and disposing a radially self-expandingprosthesis in a compressed state on a prosthesis deployment region,wherein the prosthesis deployment region is defined by a distal regionof the inner catheter and by a distal region of the outer catheter, thedistal region of the outer catheter formed by the distal region of theinner tube and the distal outer tube; wherein the support structureextends from a proximal end of the inner tube to a position that isproximal to a distal end of the inner tube and distal to a distal end ofthe medial outer tube, the support structure positioned such that theradially self-expanding prosthesis disposed in the distal region of theouter catheter extends distal of the support structure.
 11. The methodof claim 10, wherein the inner tube comprises PTFE and the distal,medial, and proximal outer tubes comprise polyether block amide.
 12. Themethod of claim 11, wherein the medial and proximal outer tubes furthercomprise a dye.
 13. The method of claim 11, wherein the polyether blockamide of the distal and medial outer tubes has a lower Shore D durometerthan the polyether block amide of the proximal outer tube.
 14. Themethod of claim 13, wherein the Shore D durometer of the distal andmedial outer tubes is 63±15 and the Shore D durometer of the proximalouter tube is 72±15.
 15. The method of claim 10, wherein the supportstructure comprises metal filaments.
 16. The method of claim 15, whereinthe metal filaments are in the form of a braid.
 17. The method of claim10, further comprising coating an inner surface of the inner tube withsilicone.
 18. A method for forming a prosthesis delivery systemcomprising: providing an outer catheter with a manifold at a proximalend, the outer catheter comprising a multi-layer wall defining a lumen,the multi-layer wall comprising: an inner tube with a distal region, aproximal region, and a medial region extending between and connectingthe distal and proximal regions; a distal outer tube bonded to thedistal region of the inner tube, wherein the distal outer tube and thedistal region of the inner tube are either translucent or transparent; amedial outer tube bonded to the distal outer tube and the medial regionof the inner tube; a proximal outer tube bonded to the medial outer tubeand the proximal region of the inner tube, wherein the proximal outertube is opaque; and a support structure interposed between the innertube and a proximal portion of the distal outer tube; providing an innercatheter with a handle at a proximal end, the inner catheter comprisinga wall defining a lumen, the wall comprising a first inner catheterpolymer; positioning the inner catheter in the lumen of the outercatheter, the inner catheter movable axially relative to the outercatheter; and disposing a radially self-expanding prosthesis in acompressed state on a prosthesis deployment region, wherein theprosthesis deployment region is defined by a distal region of the innercatheter and by a distal region of the outer catheter, the distal regionof the outer catheter formed by the distal region of the inner tube andthe distal outer tube; wherein the radially self-expanding prosthesisdisposed on the prosthesis deployment region extends distal of thesupport structure.